Big Boules - Cooking temp and times

Hello all,

Since getting into this a couple months ago, I've discovered that I really like big loaves of bread. Basically along the lines of FWSY's 1.8 kilo boule (p. 172), i.e. making a 1000 g flour batch of dough and not splitting it into two loaves.

I'm generally baking at ~475 on a pizza stone (with a pan below for 1 cup of hot water at the start of the bake).

I'm looking for any general recommendations that you might care to offer based on what you see, but in particular I am wondering about how long to bake for. Can I just bake to the color I want? Or do I need to worry about baking all the way through the loaf?

This one I only did 30 minutes, opting for a color that a majority of my audience would appreciate. Also I basically turned off the heat after the first 15 minutes as I was afraid that the crust was going to get too dark before the loaf was fully cooked. After cutting this morning, I find the interior a bit shy of what I consider fully cooked. But I just had a sandwich with a couple of toasted pieces and find it nothing to complain about.

Recipe starting point was FWSY's pain de campagne. 200g flour from levain, 200g whole wheat, 50g rye, 550g KA bread flour. 78% hydration.

Thank you for any advice you care to offer.